How TOKENIZERS_PARALLELISM will affect vLLM?

[Junjie-Chu]

When I run vLLM, sometimes I will meet

To disable this warning, you can either:
	- Avoid using `tokenizers` before the fork if possible
	- Explicitly set the environment variable TOKENIZERS_PARALLELISM=(true | false)
huggingface/tokenizers: The current process just got forked, after parallelism has already been used. Disabling parallelism to avoid deadlocks...

So when will this warning appear?
If I set TOKENIZERS_PARALLELISM=false, how the vLLM will be affected?
Could anyone help?

[vadimkantorov]

Also got hit by this :( Curious, what is the reason